Field emission devices (FEDs) are well known in the art and commonly employed in applications requiring an available source of electrons for operation. One such application is an FED display which utilizes pluralities of FEDs, in groups or individually, which emit electrons to energize a cathodoluminescent material that has been deposited onto a surface of a viewing screen or display faceplate. The emitted electrons originate form an FED emitter electrode at a region of geometric discontinuity of small radius of curvature such as a sharp edge or tip. Electron emission is induced by application of potentials of appropriate polarization and magnitude to the various electrodes of the FED display.
FED displays are generally flat displays and differ from cathode ray tube displays in that information is not impressed onto the viewing screen by means of a scanned electron beam, but rather by selectively controlling the rate of electron emission from individual FEDs or select groups of FEDs that form an array comprising the FED display. This method of imparting information to the viewing screen of a display device is termed "pixel addressing" since individual FEDs or select groups of FEDs can be associated with distinct picture elements (pixels) of the viewing screen.
In some instances it is desirable to provide active addressing of the various pixel drivers by employing active switching devices. Commonly used display addressing methods of the prior art utilize discrete active switching devices that reside beyond the extent of the display, and active semiconductor switching devices deposited directly within the display. In the former instance, discrete switching devices add to the complexity of system manufacture, size, and cost while reducing operating efficiency and reliability. In the latter instance, deposited semiconductor switches suffer from poor performance such as slow switching speed, low carrier mobility, high leakage current, and fabrication complexity. Incorporating semiconductor switches onto a substrate which contains the FED pixel drivers would necessarily require an increase in fabrication complexity.
Accordingly, there exists a need for an improved active switching technique for FED display devices that provides relief from at least some of the shortcomings of the prior art.